This application claims priority to U.S. Provisional Application Ser. No. 61/472,149, filed Apr. 5, 2011 and 61/540,526, filed Sep. 28, 2011, each of which is incorporated herein by reference in its entirety. The effectiveness of protein pharmaceuticals depends heavily on the intrinsic pharmacokinetics of the natural protein. Because the kidney generally filters out molecules below 60 kDa, efforts to reduce clearance have focused on increasing molecular size through protein fusions, glycosylation, or the addition of polyethylene glycol polymers (i.e. PEG). For example, fusions to large long-lived proteins such as albumin or the Fc portion of an IgG, the introduction of glycosylation sites, and conjugation with PEG (5-7) have been used. Through these methods, the in vivo exposure of protein therapeutics has been extended.
Pre-proglucagon is a 158 amino acid precursor polypeptide that is processed in different tissues to form a number of different proglucagon-derived peptides, including glucagon, glucagon-like peptide-1 (GLP-I), glucagon-like peptide-2 (GLP-2) and oxyntomodulin (OXM), that are involved in a wide variety of physiological functions, including glucose homeostasis, insulin secretion, gastric emptying, and intestinal growth, as well as the regulation of food intake. Glucagon is a 29-amino acid peptide that corresponds to amino acids 33 through 61 of pre-proglucagon, while GLP-I is produced as a 37-amino acid peptide that corresponds to amino acids 72 through 108 of pre-proglucagon.
When blood glucose begins to fall, glucagon, a hormone produced by the pancreas, signals the liver to break down glycogen and release glucose, causing blood glucose levels to rise toward a normal level. GLP-1 has different biological activities compared to glucagon. Its actions include stimulation of insulin synthesis and secretion, inhibition of glucagon secretion, and inhibition of food intake. GLP-1 has been shown to reduce hyperglycemia (elevated glucose levels) in diabetics. Exendin-4, a peptide from lizard venom that shares about 50% amino acid identity with GLP-I, activates' the GLP-I receptor and likewise has been shown to reduce hyperglycemia in diabetics.
Glucose-dependent insulinotropic peptide (GIP) is a 42-amino acid gastrointestinal regulatory peptide that stimulates insulin secretion from pancreatic beta-cells in the presence of glucose. It is derived by proteolytic processing from a 133-amino acid precursor, preproGIP.
There is evidence that the combined effect of GLP-1 and GIP may account for the incretin effect (Keiffer, et al., Endocrinology, Vol 136, 3585-3596, 1995). Both proteins are degraded by dipeptidyl peptidase IV. Both hormones or analogs thereof have been the subject of recent clinical trials (NCT00239707; Irwin, et al., Clinical Endocrinology and Metabolism, Volume 23, Issue 4, Pages 499-512 (August 2009)). GLP-1 (7-36) amide alone is not very useful for treatment, since it must be administered by continuous subcutaneous infusion. Several long-lasting analogs of GLP-1 having insulinotropic activity have been developed, and two, exenatide (Byetta) and liraglutide (Victoza), have been approved for use in the U.S. The main disadvantage of these GLP-1 analogs is they must be administered by subcutaneous injection.
WO/2010/011439 describes a GLP-1/GIP chimeric protein with dual tropism for the GIP receptor and the GLP-1 receptor. The peptides described in WO/2010/011439, however, are subject to increased degradation due to their inherent chemical structure and lack of patterned polypeptide backbone amino acids.
There is a need to design and manufacture analogs of glucagon, GIP, and GLP-1 to control, prevent, and treat metabolic disorders including diabetes and obesity. There is a need to design and manufacture analogs of glucagon, GIP, and GLP-1 to enhance the half-life of a bioactive molecules. There is a need for analogs of glucagon, GIP, and GLP-1 that exhibit increased conformational constraints or increased conformational flexibility and greater half-lives. There is a need for analogs of glucagon, GIP, and GLP-1 that are less suspectible to degradation and increase affinity of pharmaceutical compositions and/or other agents to bind target molecules in a subject's body, such as GIP receptor. Increased conformational constraints may lock the active domain of the polypeptides or chimera into their active state. Increased conformational flexibility of the polypeptide may yield a high affinity selectivity for the naturally occurring polypeptide's natural biological target. There is a need for use of such analogs, compositions comprising such analogs, and methods of using the compositions as pharmaceutically active agents to treat disease in animals. New polypeptide analogs are disclosed that may provide one of more increased half-life, reduced degradation upon administration, reduced degradation upon solubilization, increased conformational constraints and that produce the same or greater biological effect as compared to a pharmaceutical agent unmodified by the analog. The present invention addresses these and other needs associated with treatment and prevention of disease that implicate dysfunction of biological systems involving naturally occurring polypeptides.